The Philosopher Confucius (551-479 BC) - "do not do to others what you would not like yourself; then your public life will arouse no ill-will nor your private life any resentment".
Sound familiar?
Lev 19:18 Thou shalt not avenge, nor bear any grudge against the children of thy people, but thou shalt love thy neighbour as thyself: I [am] the LORD.
Leviticus is a bit older than Confusion.
True, the golden rule had been expounded previously. But that is only one part of Christian morality. You will not find any Christ before Christ.